1. Field of the Invention
The present invention relates to techniques which can simply and highly accurately detect a counterfeit of a digital data.
2. Description of the Related Art
In recent automotive vehicles, in-vehicle control units perform electronic controls of an engine, a brake system, and various vehicular components. In the engine control, in order to cope with a compatibility of both an engine output and an exhaust quality, optimum control data obtained through various experiments are used. On the other hand, in part of automotive markets, an illegal modification on the control unit such that optimally set control data are rewritten in order to improve only the engine output without a reduction in the exhaust quality taken into consideration has been made. To cope with such an illegal modification as described above, in a North America, an automotive manufacturer is obliged to output a CVN (Calibration Verification Number) to a terminal in order to prevent the illegal modification of the control unit as a series of exhaust gas limitation reinforcements.